Sync feature flag with the outcomes service

closes OUT-3886

flag=account_level_mastery_scales

test plan:
  - test with associated outcome_service patch set
  - provision outcomes service on a canvas account
    not in the default shard
  - go to account settings, then feature options
  - enable the "Account and Course Level Outcome Proficiencies"
    feature option
  - confirm in the outcomes service that the service
    feature flag was also enabled:
    % switch_to_shard! 'host.outcomes.docker'
    > Outcomes.flipper[:context_proficiencies].enabled? Account.default
  - perform same test when disabling the feature option
    in canvas

Change-Id: I267ff4acb12c52ef0897ce738dc4c847ee708926
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/249764
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Michael Brewer-Davis <mbd@instructure.com>
Reviewed-by: Pat Renner <prenner@instructure.com>
QA-Review: Pat Renner <prenner@instructure.com>
Product-Review: Augusto Callejas <acallejas@instructure.com>

app/models/outcomes_service/service.rb

@@ -47,8 +47,32 @@ module OutcomesService
         end
       end
 
+      def toggle_feature_flag(root_account, feature_flag, state)
+        feature_flag_url = "#{url(root_account)}/api/features/#{state ? 'enable' : 'disable'}"
+        response = CanvasHttp.post(
+          feature_flag_url,
+          headers_for(root_account, 'features.manage'),
+          form_data: {
+            feature_flag: feature_flag
+          }
+        )
+        return unless response && response.code != '204'
+
+        Canvas::Errors.capture(
+          "Unexpected response from Outcomes Service toggling feature flag",
+          status_code: response.code,
+          body: response.body
+        )
+      end
+
       private
 
+      def headers_for(context, scope, overrides = {})
+        {
+          'Authorization' => OutcomesService::Service.jwt(context, scope, overrides: overrides)
+        }
+      end
+
       def settings(context)
         context.root_account.settings.dig(:provision, 'outcomes') || {}
       end

config/feature_flags/outcomes_feature_flags.yml

@@ -42,6 +42,7 @@ account_level_mastery_scales:
   display_name: Account and Course Level Outcome Proficiencies
   description: Allows Account & Course Level mastery scales and calculation,
     replacing per-outcome criterion ratings & calculation methods
+  after_state_change_proc: mastery_scales_after_change_hook
 usage_rights_discussion_topics:
   state: hidden
   applies_to: RootAccount

lib/feature_flags/hooks.rb

@@ -99,5 +99,23 @@ module FeatureFlags
         )
       end
     end
+
+    def self.mastery_scales_after_change_hook(_user, context, _old_state, new_state)
+      if context.is_a?(Account) && OutcomesService::Service.enabled_in_context?(context)
+        OutcomesService::Service.send_later_if_production_enqueue_args(
+          :toggle_feature_flag,
+          {
+            priority: Delayed::LOW_PRIORITY,
+            n_strand: [
+              'outcomes_service_toggle_context_proficiencies_feature_flag',
+              context.global_root_account_id
+            ]
+          },
+          context.root_account,
+          'context_proficiencies',
+          new_state == 'on'
+        )
+      end
+    end
   end
 end

spec/models/outcomes_service/service_spec.rb

@@ -83,5 +83,27 @@ describe OutcomesService::Service do
         )
       end
     end
+
+    describe '.toggle_feature_flag' do
+      def expect_post(url)
+        expect(CanvasHttp).to receive(:post).with(
+          url,
+          hash_including('Authorization'),
+          form_data: {
+            feature_flag: 'fake_flag'
+          }
+        )
+      end
+
+      it 'enables feature flag' do
+        expect_post('http://canvas.test/api/features/enable')
+        Service.toggle_feature_flag(root_account, 'fake_flag', true)
+      end
+
+      it 'disables feature flag' do
+        expect_post('http://canvas.test/api/features/disable')
+        Service.toggle_feature_flag(root_account, 'fake_flag', false)
+      end
+    end
   end
 end